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Abstract #4265

Dependence of Rotating Frame Relaxation Rates on Frequency Offset: Spin-Lock Versus Adiabatic Rotation

Silvia Mangia1, Timo Liimatainen1, Michael Garwood1, Shalom Michaeli1

1Radiology, University of Minnesota, Minneapolis, MN, USA

In the present work we investigate the frequency offset dependency of the rotating frame longitudinal, R, and transverse, R, relaxation rate constants during continuous-wave spin-lock irradiation and during hyperbolic secant adiabatic full passage pulses. We demonstrate, both theoretically and experimentally, that R and R induced by dipolar interactions and anisochronous exchange during hyperbolic secant pulses are minimally dependent on the frequency offsetwithin the bandwidth of the pulse, as opposite to continuous-wave irradiation. This is a unique advantage for MRS applications in vivo, because it allows "one shot" data acquisition over a wide range of chemical shift.